Walt Disney Co has opened the gates to its first theme park in China, prompting a rush from thousands of gathered Mickey Mouse enthusiasts.

The enthusiasts were the first to storm Treasure Cove, ride the Roaring Rapids or visit Disney's tallest castle.

Disney's largest overseas investment at 5.5 billion dollars, the park was a bet on China's middle class and booming domestic tourism.

The U.S. firm expressed the hope it would offset an otherwise lackluster international theme park business, better known for cash-burning sites such as Euro Disney.

``This is one of the proudest and most exciting moments in the history of the Walt Disney Company,’’ the Chief Executive Officer Bob Iger said at the official ribbon cutting ceremony on Thursday.

Iger and Chinese Vice Premier Wang Yang read out letters of support from Barack Obama and President Xi Jinping.

Not everything had gone quite to plan though.

The opening gala meant to be a bonanza of fireworks, live music and dance, was rained off on Wednesday night, while at Disney's park in Orlando, Florida, a young boy was grabbed by an alligator and killed.

Disney, though, sees China as its biggest opportunity since Walt Disney bought land in Florida in the 1960s for what is now Walt Disney World - the world's most-visited theme park.

With that in mind, Main Street had been replaced by Mickey Avenue to reduce the feel of Americana, while attractions included the Chinese-style Wandering Moon tea house, a Chinese Zodiac-themed garden and a Tarzan musical featuring Chinese acrobats.

Disney estimated 330 million people within a three-hour radius of Shanghai would be able to afford to come to the park.

That included Zhao Qiong, 36, who was one of the first visitors inside the park on Thursday with her 4-year-old daughter.

``Since she was young, my little girl has always loved Disney princesses, so I wanted to bring her to the park to fulfill her dream,’’ she said.